Conventionally, an in-vehicle communication terminal carried by a vehicle and configured to determine whether the vehicle is in a stolen condition based on a detection result that indicates that a station number of a base station that is serving as a waiting station has changed after the vehicle is put in a parking condition is available (refer to, for example, Japanese patent document JP-A-H11-170981).
Further, an in-vehicle communication terminal that is configured to send an emergency report by transmitting positional information derived from GPS positioning by an GPS engine to a center terminal or a user terminal after watching a vehicle that is put into a parked condition and determining that the vehicle is in a stolen condition if a travel distance of the parked vehicle reaches a certain value is also available. In this case, if the communication terminal is configured to determine whether the travel distance after parking has reached the certain distance based on the positional information derived from the GPS measurement conducted by the GPS engine, the GPS engine has to be periodically performing the GPS measurement for calculating the travel distance of the vehicle.
However, in the above configuration that periodically performs the GPS measurement by using the GPS engine, the electricity consumption by the GPS engine is not negligible even when the probability of vehicle theft is extremely low or substantially none. As a result, the GPS engine may cause a battery down (i.e., so-called “Dead battery”) if the GPS engine is operated only by the vehicle's battery for performing the GPS measurement.